body {
  margin: 0;
  padding: 0;
}

.card {
  background-color: #eee;
  border: 1px solid #ddd;
  padding: 15px;
  box-shadow: 3px 3px 3px #ccc;
  margin: 10px;
  min-height: 100px;
}

.btn {
  margin-right: 10px;
  margin-top: 10px;
  padding: 8px 10px;
  border-radius: 5px;
  border: 1px solid #bbb;
  padding: 8px 10px;
  background-color: #fff;
  color: #1c19ad;
  cursor: pointer;
}

/* 未使用的 CSS */
.unused-class {
  color: red;
}
.xxxxxx {
  background-color: blue;
}
